The present invention relates generally to electric meters and, more specifically, to an electric meter with an apparatus for supporting and positioning a sensing head for use with a photo-optic pulse initiator.
Electric utility companies have, for many years, used electric meters to measure the electric energy consumption of its customers. Many different types of electric meters have been used, such as kilowatt-hour meters, demand meters and time-of-use meters. A typical electric meter comprises a base member that can be attached to a portion of a consumer's dwelling. A frame structure is rigidly attached to the base for the purpose of supporting the internal components of the meter. Usually, the frame member is metallic and is shaped to receive a vertical shaft in rotatable association therewith. This vertical shaft is attached to a disc which is rotatable in response to electrical energy usage. This electroconductive disc, or armature, is typically mounted for rotation about the vertical axis of the shaft which is supported by one or more bearings. U.S. Pat. No. 3,397,929, which issued on Aug. 20, 1968 to Gill et al, discloses a bearing assembly that includes a stator unit and a rotor unit mounted for relative rotation. A magnetically supported shaft is disclosed in U.S. Pat. No. 3,413,550, which issued on Nov. 26, 1968 to Wright. It comprises a rotatable electroconductive armature and two damping magnet fields which vary in cross-section oppositely in a direction parallel to the armature axis. These two patents disclose bearings that provide support for the disc and vertical shaft in such a way so as to minimize friction between the stationary and rotating components.
In a typical application, an electric meter is provided with a dial register for visually indicating the cumulative energy consumption of an electric energy consumer. The front face of the register typically comprises a plurality of dials, or pointers, that rotate with shafts to which they are attached. The register generally has a plurality of rotatable shafts that are connected together, by appropriate gearing, in a decade relationship. The pointer and shaft that represent the least significant digit of the kilowatt-hour reading are associated, in a gearing relationship, with the vertical shaft of the rotatable disc. A worm gear portion of the vertical shaft engages appropriate transmission gearing that permits the vertical shaft to cause the entire gear train of the register to be affected in response to the consumer's electrical energy consumption.
Recent developments in the field of electric energy measurement have resulted in alternative measuring techniques which alleviate the need for a mechanical dial register as described above. These improved techniques relate to the use of electronic signals that are responsive to the rotation of the electric conductive disc itself. In a typical application of this type of meter, the rotatable disc is marked in such as way so as to provide both reflective and non-reflective portions on its surface. One or more sensing heads are disposed proximate the surface of the rotatable disc and are provided with light sources and light sensitive components. Each light source, such as a light emitting diode, is directed toward the surface of the disc in such a way so as to direct a beam of light at a preselected angle toward the surface. One or more light sensitive components, such as photodiodes or phototransistors, are each associated with a light emitting diode and disposed in such a way so as to receive reflected light from the surface of the disc. When a reflective portion of the disc surface passes proximate the sensing head, the light beam is reflected by the disc's surface and received by the photosensitive device. Alternatively, when a non-reflective surface passes proximate the sensing head, no light is reflected and appropriate electronic circuitry can be provided that distinguishes between the presence and absence of light. As the disc rotates, reflective and non-reflective portions of its surface sequentially pass beneath the sensing head and appropriate pulses can be generated in response to the changes from reflective to non-reflective states. This technique permits electronic circuitry to count the pulses and maintain a count of the number of revolutions of the rotatable disc. U.S. Pat. No. 4,034,292, which issued on July 5, 1977 to McClelland, discloses a direction sensitive opto-electronic pulse initiator for electrical meters. U.S. Pat. No. 4,047,024, which issued on Sept. 6, 1977 to Henderson, discloses a photoelectric pulse initiator that includes a single track pattern and sensing assembly. A direct input photoelectric pulse initiator for meter telemetry and recording systems is disclosed in U.S. Pat. No. 3,943,498 which issued on Mar. 9, 1976 to McClelland et al and an improved radiometric pulse initiator having a reflective pattern drum is disclosed in U.S. Pat. No. 3,878,391, which issued on Apr. 15, 1975 to McClelland et al.
When photoelectric sensing heads are used to count the rotations of the rotatable disc, mechanical registers can be replaced by improved indicator panels. For example, vacuum fluorescent display Style number LD8191/FIP9J5B made by the Nippon Electric Company can be used. Appropriate electronic circuitry is required to count the pulses received by the sensing head assembly and store the results in the memory of a microprocessor and associated random access memory (RAM) devices. After converting the pulse count to a kilowatt-hour value, by multiplication by an appropriate constant, the kilowatt-hour consumption can be stored and displayed on the indicating panel.
The present invention provides an apparatus that enables a conventional electromechanical meter, using a mechanical dial register, to be converted to a meter that utilizes a sensing head assembly and a pulse initiator to measure electrical energy consumption as a function of the number of rotations of a rotatable disc. This enables a conventional electric meter to be retrofitted to include electronic capabilities. By using the present invention, an operator can remove the mechanical register from an electric meter and replace it with a preassembled structure that contains all the required components to convert the meter to one which utilizes sensing heads, a photo-optic pulse initiator and a indicator panel. Furthermore, the present invention provides dimensionally accurate positioning of the sensing heads in relation to the rotatable disc in such a way that it is applicable to both single-phase and three-phase meters. The present invention utilizes the existing base, frame and armature structure of the existing meter along with all the stator conductors which remain rigidly attached to the base.
When sensing heads and pulse initiator are utilized to measure electrical energy consumption, special rotatable discs are usually employed. However, the present invention permits conventional electroconductive discs to be used. This avoids the necessity of replacing the vertical shaft and rotatable disc of the original meter along with the necessary recalibration that would otherwise be required.
The present invention comprises a frame member which is generally similar in appearance to the back plate of the conventional register with which it will be utilized. Attached to the frame member is a bracket. The present invention utilizes a flexible means for supporting the plurality of electronic components required to count pulses received from the above-mentioned sensing heads. The flexible supporting means, or flexible circuit, can be of the type that are available in commercial quantities from the Buckbee-Mears Company. This flexible means for supporting the electronic components comprises a plurality of conductive paths that are connected in electrical communication with the electronic components. The electronic components comprises resistors, capacitors and semiconductive devices. Furthermore, one or more microprocessors and related memory devices can be connected in electrical communication with the conductive paths of the flexible component supporting means.
The flexible circuit is supported by the bracket discussed above. The bracket is shaped to receive a portion of the flexible supporting means in sliding association and retain the circuit in such a way so as to prevent its movement after assembly. The bracket also has at least one retaining clip that is shaped to receive a sensing head. The sensing head is shaped to receive a first and a second device is a preselected alignment relation with each other. In a preferred embodiment of the present invention, the first device is a light source, such as a light emitting diode, and the second device is a light sensitive component, such as a phototransistor. The sensing head has two openings which are shaped to receive these devices and retain them in a preselected alignment relation. The particular alignment of the first and second devices is such that a light beam can be directed from the light emitting diode toward the surface of the rotatable disc of the electric meter. The second device is aligned in such a way so as to receive the reflected light beam from the surface of the rotatable disc.
In order to provide for the use of the present invention with different sizes of rotatable discs and different vertical positions of the rotatable discs, a spacer is provided in order to offset the position of the bracket and sensing heads from the back plate, or frame member, of the present invention.
The present invention provides an apparatus that permits a conventional electromagnetic meter to be retrofitted in the field with sensing heads, pulse initiators and related circuitry. Furthermore, the present invention can be used to manufacture improved electric meters, prior to delivery and installation in the field.